59629855201QXX View Datasheet(PDF) - Aeroflex UTMC
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59629855201QXX Datasheet PDF : 62 Pages
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2.0 Register File
The UT69R000 has a register-oriented architecture. The
registers within the machine fall into two categories, general
purpose and specialized registers. All registers are accessible
to the programmer through the instruction set. The programmer
uses data from these registers to perform arithmetic and logical
functions, alter program flow, detect various system and
machine faults, determine machine status, control UART and
timer functions, and for exception handling.
2.1 General Purpose Registers
Figure 5 shows the UT69R000’s 20 general purpose registers.
The UT69R000 normally accesses these registers as single-
word 16-bit registers although the machine can concatenate
these registers into 32-bit double-word register pairs. When the
programmer uses the general purpose registers as a double-
word register pair, the most significant 16 bits of the 32-bit
words are stored in the even-numbered register of the register
pair. For instance, if a 32-bit word is stored in Register Pair
XR6, the most significant word is stored in register R6 and the
least significant word is stored in register R7.
In addition to the 20 general purpose registers, the UT69R000
has a 32-bit accumulator (ACC). The ACC is normally a
destination register, although under certain circumstances it
can be the source register (INR RD, ACC). The accumulator
retains the most significant half of the product during a multiply
instruction or the remainder during a divide operation.
16 BITS 16 BITS
R0
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16
R17
R18
R19
ACCUMULATOR
CONCATENATED 32-BIT
REGISTER PAIR
XR0
XR2
XR4
XR6
XR8
XR10
XR12
XR14
XR16
XR18
ACC
Figure 5. General Register Set
2.2 Specialized Registers
The UT69R000 has 13 special purpose registers. These
registers control machine configuration, report status, and
interrupts. Below is a list of the special purpose registers. The
values in the brackets indicate the power-up condition.
1. Stack Pointer Register (SP) [XXXX (hex)]
2. System Status Register (STATUS) [XXXX (hex)]
3. UART Receiver Buffer Register (RCVR)
[XX00 (hex)]
4. UART Transmitter Buffer Register (TXMT)
[XX00 (hex)]
5. Pending Interrupt Register (PI) [0000 (hex)]
6. Fault Register (FT) [0000 (hex)]
7. Interrupt Mask Register (MK) [XXXX (hex)]
8. Status/Output Discrete Register (SW)
[XXFF (hex)]
9. Instruction Counter Register (IC) [0000 (hex)]
10. Instruction Counter Save Register (ICS)
[XXXXX (hex)]
11. Instruction Register (IR) [0000 (hex)]
12. Timer A (TA) [0000 (hex)]
13. Timer B (TB) [0000 (hex)]
The instruction set provides access to most of the special
purpose registers.
2.2.1 Register Description
Stack Pointer Register
The UT69R000 uses the 16-bit Stack Pointer Register as an
address pointer on PUSH and POP instructions. The machine
pre-increments (POP) and post-decrements (PUSH) the Stack
Pointer contents. The programmer loads and stores the SP by
executing the INR and OTR commands to the stack pointer.
Bit 15 is the most significant bit, the least significant bit is bit
zero.
System Status Register
The System Status Register provides status information on the
UT69R000’s internal operation, including status of the internal
UART. The register is read via the INR Rd, STATUS
instruction. Bit definitions follow.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
M
T
I
RO F P C T D
C P ZNVJ M
B
E EE E EN ER
E
E
MSB
LSB
Figure 6. The System Status Register (STATUS)
6
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